This invention relates generally to computer systems, and more particularly to hand-held computer systems which permit handwritten input via a dual-function display.
Computerized personal organizers are useful for storing, transporting and rapidly recalling information. Smaller hand-held organizers now fit easily in a pocket, a purse or a briefcase and can be brought to a meeting or used on a train, for example. Many people who, for example, organize schedules, make appointments, recall phone numbers and keep diaries rely on these devices daily.
In the past, computerized personal organizers have employed a keypad for information input. However, keypads associated with hand-held organizers are typically difficult to use. The keys are small, difficult to see, and cumbersome to operate. Computerized organizers capable of receiving handwritten input have recently been developed, in part, to answer these problems. These devices are referred to variously as pen-based computer systems, computerized notepads, personal digital assistants (PDA's), electronic personal organizers, etc.
Pen-based computers may rely on a pointer such as a stylus (sometimes referred to as a "pen") or a mouse to input desired information to the computer system. A stylus is typically preferred over the mouse because of enhanced portability and ease of use. Pen-based computers generally include a dual function display assembly which acts simultaneously as an input device ("input tablet") and as an output device. The display assembly typically includes a liquid crystal display (LCD) or other portable display having a matrix of pixels capable of displaying text, graphics, etc. A variety of different types of input tablets can be used, including a much sensitive membrane positioned over the LCD. The input tablet senses the position of the tip of the stylus on the viewing screen and provides this positional information to the computer's central processing unit (CPU). During output, the display assembly presents computer-generated images on the screen in the form of text, graphics, etc. These images are viewed by the user and may, for example, prompt a user to act or provide feedback to the user.
State-of-the art pen-based computers recognize handwritten text from the input tablet of the dual function display. Not infrequently, however, the pen-based computer fails to recognize handwritten words correctly. To enhance handwriting recognition, many pen-based computers employ adaptive handwriting learning. Through the use of a user-specific database, the pen-based computer adapts its handwriting recognition techniques to optimize user-specific handwriting recognition. The pen-based computer continually updates the user-specific database as the user inputs words into the computer system. Additionally, the computer system recalls handwriting style and letter style preference information previously input into the user-specific database by the user. With these techniques, the computer system better reads, converts and stores handwriting input (sometimes called electronic "ink") for a particular user.
Pen-based computers are useful, portable and greatly desired. An owner or primary user of such a device may often desire to share the pen-based computer with others. This causes at least two problems with handwriting recognition. First, the pen-based computer has greater difficulty in recognizing the guest user's handwriting because it has adapted its recognition ability to the primary user's handwriting. Second, during use by a guest, the pen-based computer adapts a handwriting recognition database to the guest's handwriting. After prolonged use by the guest, the recognition capability of the computer is less well adapted to the primary user's handwriting. Handwriting recognition can thus be degraded when different users operate the computer.